This might be a dumb question, but I'm going to ask anyway: Do you think there is any benefit if I spray the grapes with Star San before I put them in the wort? I heard that Star San does not kill yeast, but will kill most bacteria. Thoughts?

1) Early on you'll get some bacterial growth, including some stuff we'd normally want to avoid,
2) Between days 10 and 30 of the ferment, yeast will come to dominate, as the dropping pH and climbing alcohol levels of the wort kill off most of the bacteria.
3) Over the next few months the culture will mature, ending up with a (hopefully) tasty mix of wild yeasts and some brew-friendly bacteria.

If you're worried about the bacteria you can heavily hop the wort (bittering additions are all that is really needed). Alpha acids have some anti-microbrial effects but are generally harmless to yeast.